#include <bits/stdc++.h>
using namespace std;
int max(int a,int b){
	int max;
	if(a>=b){max=a;}
	else{max=b;}
	return max;
}
int x[1002][1002];
int main() {
	string a,b;
	getline(cin,a);
	getline(cin,b);
	for(int i = a.length();i>=0;i--){
		for(int j = b.length();j>=0;j--){
			if(i==a.length() or j==b.length()){
				x[i][j]=0;
			}
			else if(a[i]==b[j]){
				x[i][j]=x[i+1][j+1]+1;
			}
			else{
				x[i][j]=max(x[i][j+1],x[i+1][j]);
			}
		}
	}
	cout<<x[0][0]<<endl;
	for(int i = 0;i<a.length();i++){
		for(int j = 0;j<b.length();j++){
			cout<<x[i][j]<<' ';
		}
		cout<<endl;
	}
	cout<<a<<endl<<b<<endl;
	vector<char> v;
	int q=a.length()-1,w=b.length()-1,ans=0;
	while(ans!=x[0][0]){
		cout<<a[q]<<' '<<b[w]<<endl;
		if(x[q][w]==x[q][w-1]+1 && x[q][w]==x[q-1][w]+1 && x[q][w]==x[q-1][w-1]+1){ans++;v.push_back(a[q]);q--;w--;}
		else if(x[q][w-1]==x[q-1][w]){w--;q--;cout<<x[q][w]<<x[q-1][w-1]<<x[q-1][w]<<x[q][w-1]<<endl;}
		else if(x[q][w-1]>x[q-1][w]){w--;}
		else{q--;}
	}
	for(int i = ans-1;i>=0;i++){
		cout<<v[i];
	}
	cout<<endl;
	return 0;
}

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